As companies rely more and more on e-commerce, on line transaction processing, and databases, the amount of information that needs to be managed and stored can intimidate even the most seasoned of network managers.
While servers do a good job of storing data, their capacity is limited, and they can become a bottleneck if too many users try to access the same information. Instead, most companies rely on peripheral storage devices such as tape libraries, RAID disks, and even optical storage systems. These storage devices are effective for backing up data online and storing large amounts of information. By hanging a number of such devices off of a server, a network administrator can create a server farm that can store a substantial amount of data for the enterprise.
But as server farms increase in size, and as companies rely more heavily on data-intensive applications such as multimedia, this traditional storage model is not quite as useful. This is because access to these peripheral devices can be slow, and it might not always be possible for every user to easily and transparently access each storage device. Recently, a number of vendors have been developing Storage Area Network (SAN). SANs provide more options for network storage, including much faster access than the peripheral devices that operate as Network Attached Storage (NAS) and SANs further provide flexibility to create separate networks to handle large volumes of data.
A SAN is a high-speed special-purpose network or subnetwork that interconnects different kinds of data storage devices with associated data servers on behalf of a larger network of users. Typically, a storage area network is part of the overall network of computing resources for an enterprise. A SAN is usually clustered in close proximity to other computing resources such as IBM S/390 mainframes but may also extend to remote locations for backup and archival storage, using wide area network carrier technologies such as ATM or Synchronous Optical Networks. A SAN can use existing communication technology such as optical fiber ESCON or Fibre Channel technology.
SANs support disk mirroring, backup and restore, archival and retrieval of archived data, data migration from one storage device to another, and the sharing of data among different servers in a network. SANs can incorporate subnetworks with network-attached storage systems.
Although SANs hold much promise, they face a significant challenge. Bluntly, consumers expect a lot of their data storage systems. Specifically, consumers demand that SANs provide network type scalability, service and flexibility, while at the same time providing data access at speeds that compete with server farms. This can be quite a challenge, particularly in environments where the dynamics of client data usage vary greatly and tend to change over time. For example, the speed at which a storage system can respond to a client demand, depends at least in part on the resources available on the server that is processing the request. However, client requests for data can be bursty and can tend to request certain portions of the stored data much more frequently than some of the other data. Moreover, client requests can follow patterns where certain portions of the stored data are commonly, although not always, requested along with other portions of the stored data.
In enterprise storage systems, different techniques have been developed to deal with the fact that certain portions of the stored data are requested more frequently than other portions. Further, striping techniques have been developed to allow enterprise storage systems to form patterns of data blocks that are more efficiently read from the disk storage devices. However, these techniques are readily implemented on the typical enterprise storage system by modifying the gateway or switch to monitor client requests and control how data is stored on the underlying storage media. For storage area networks such techniques can also be employed, however they force the SAN to use a gateway or switch architecture, and this can reduce the speed at which client requests can be performed.
Accordingly, it would therefore be desirable to provide a method and system that allows storage are network to control how data is stored and managed on the systems without requiring a gateway to monitor all incoming request traffic.